Channel method for forming a capacitor

ABSTRACT

An improved method for forming a capacitor. The method includes:
     providing a carrier with a channel therein;   providing a metal foil with a valve metal with a first dielectric on a first face of the metal foil;   securing the metal foil into the channel with the first dielectric away from a channel floor;   inserting an insulative material between the metal foil and each side wall of the channel;   forming a cathode layer on the first dielectric between the insulative material;   forming a conductive layer on the cathode layer and in electrical contact with the carrier;   lap cutting the carrier parallel to the metal foil such that the valve metal is exposed; and   dice cutting to form singulated capacitors.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention claims priority to U.S. Provisional PatentApplication No. 60/927,025 filed May, 1, 2007 which is pending andincorporated by reference.

BACKGROUND

The present invention is related to an improved method for forming acapacitor. More specifically, the present invention is related to amethod for forming a capacitor utilizing a channeled substrate.

Capacitors are utilized in virtually every electronic device. Thefunction in an electronic circuit is well known and further discussionis not warranted herein. The instant disclosure is directed toimprovements in the manufacture of sheet-based capacitors.

In one method of manufacture, capacitors are formed from metal sheetswherein the general process includes oxidation, also referred to asanodization, of a metal sheet to form a dielectric. A conductive layeris formed on the dielectric. The capacitor is conventionally utilized inan electrical circuit with the metal sheet functioning as the anode andthe conductive layer functioning as the cathode, even though this can bereversed.

Small surface mount capacitors have been successfully formed fromaluminum foil. The aluminum foil, either strips or sheets, is etched toincrease the surface area and then anodized to form a thin dielectric oneach face. A conductive layer, such as a conductive polymer, is thenformed on the dielectric. If necessary, the strip is cut intorectangles. The rectangles may be combined in parallel to form acapacitor package. Terminal leads and molding are added to form asurface mountable capacitor.

Manufacturing of foil based capacitors is difficult due to the fragilenature of a thin metal foil. The present invention provides an improvedmethod for thin capacitor formation.

SUMMARY

It is an object of the present invention to provide an improved methodfor the formation of capacitors.

It is another object of the present invention to provide an improvedmethod for forming a thin capacitor from conductive sheets such as metalfoils.

A particular feature of the present invention is a method ofmanufacturing a thin capacitor from a conductive sheet requiring aminimal amount of handling of the conductive sheet.

Another particular feature of the present invention is the ability toencapsulate and immobilize the conductive sheet during formation of acapacitor from the conductive sheet.

These and other advantages, as will be realized, are provided in amethod for forming a capacitor. The method includes:

providing a carrier comprising a channel therein;providing a conductive foil or sheet, preferably comprising a valvemetal, with a first dielectric on a first face of the conductive foil;securing the conductive foil into the channel with the first dielectricaway from a channel floor;inserting an insulative material between the conductive foil and eachside wall of the channel;forming a cathode layer on the first dielectric;forming a conductive layer on the cathode layer and in electricalcontact with the carrier;lap cutting the carrier parallel to the conductive foil such that theconductive foil is exposed; anddice cutting to form singulated capacitors.

Yet another embodiment is provided in a method for forming a capacitorhaving coplanar terminations. The method includes:

providing a carrier comprising a channel therein;providing a conductive, preferably metal, foil most preferablycomprising a valve metal with a first dielectric on a first face of theconductive foil;securing the conductive foil in the channel with the first dielectricaway from a channel floor;inserting an insulative material between the conductive foil and eachside wall of the channel;forming a cathode layer on the first dielectric;forming a conductive layer on the cathode layer and in electricalcontact with the carrier;lap cutting the carrier parallel to the metal foil such that theconductive foil is exposed; anddice cutting to form singulated capacitors wherein the dice cuttingexcludes the insulative material such that at least part of the carrierremains attached to the final device.

Yet another embodiment is provided in a method for forming a capacitorhaving terminals on opposite faces. The method comprises:

providing a carrier comprising a channel therein;providing a conductive, preferably metal, foil most preferablycomprising a valve metal with a first dielectric on a first face of theconductive foil;securing the conductive foil into the channel with the first dielectricaway from a channel floor;inserting an insulative material between the conductive foil and eachside wall of the channel;forming a cathode layer on the first dielectric;forming a conductive layer on the cathode layer and in electricalcontact with the carrier;lap cutting the carrier parallel to the conductive foil such that theconductive portion of the conductive foil is exposed; anddice cutting within the insulative material such that the carrier isremoved to form a singulated capacitor.

Yet another embodiment is provided in a capacitor. The capacitor has ametal foil anode with a bottom and top. A dielectric is on the top ofthe metal foil anode. A cathode is on the dielectric opposite to themetal foil anode. A cathode lead is in electrical contact with thecathode on a first face where a second face of the cathode lead iscoplanar with the bottom of the metal foil anode. An insulator is on twoopposing sides of the cathode lead different than the first face andsecond face.

Yet another embodiment is provided in a capacitor. The capacitor has aconductive foil anode with a bottom and top. A dielectric is on the topof the conductive foil anode. A cathode is on the dielectric opposite tothe conductive foil anode. A cathode lead is in electrical contact withthe cathode on a first face where a second face of the cathode lead iscoplanar with the bottom of the conductive foil anode. An insulator ison two opposing sides of the cathode lead different than the first faceand second face.

Yet another embodiment is provided in a capacitor with a metal foilanode having a bottom and top. A dielectric is on the top of the metalfoil anode. A cathode lead is circumjacent to the metal foil anode. Acathode lead is in electrical contact with the cathode; and an insulatoris between the cathode lead and the metal foil anode.

Yet another embodiment of the present invention is provided in a methodfor forming a capacitor. The method includes:

providing a metal foil with a first edge and a dielectric on a firstface;applying an insulator to the first edge and to a second face of themetal foil opposite to the dielectric;applying a conductive layer to the dielectric and the insulator;attaching a metal strip to the conductive layer to form a capacitorprecursor;lap cutting the capacitor precursor parallel to the foil and through thefoil and the metal strip thereby exposing the metal strip and the metalfoil on a common face with an insulator therebetween.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is a schematic cross-sectional side view of a conductive foil ina carrier in accordance with the instant invention.

FIGS. 2, 3 and 4 are various schematic views of a carrier with cross-cutchannels.

FIG. 5 is a schematic cross-sectional view of the embodiment of FIG. 1after further processing.

FIG. 6 is a top schematic view of the embodiment of FIG. 5.

FIG. 7 is a schematic cross-sectional view of the embodiment of FIG. 5after further processing.

FIG. 8 is a schematic cross-sectional view of the embodiment of FIG. 7after further processing.

FIG. 9 is a schematic cross-sectional view of the embodiment of FIG. 8illustrating lap and dice lines.

FIG. 10 is a top schematic view illustrating the dice lines.

FIG. 11 is a schematic cross-sectional view of an embodiment of afinished capacitor of the present invention.

FIG. 12 is a schematic bottom view of the finished capacitor illustratedin FIG. 11.

FIG. 13 is a schematic cross-sectional view of an embodiment of afinished capacitor of the present invention.

FIG. 14 is a schematic bottom view of the finished capacitor illustratedin FIG. 13.

FIG. 15 is a schematic cross-sectional view of an embodiment the presentinvention illustrating lap and dice lines.

FIG. 15 a illustrates an alternative embodiment of the presentinvention.

FIG. 16 is a schematic perspective view of a carrier of the presentinvention.

FIG. 17 is a top view of an embodiment of the present invention.

FIG. 18 is a cross-sectional schematic view taken along line 18-18 ofFIG. 17.

FIG. 19 is a cross-sectional schematic view of an embodiment of theinvention.

FIG. 20 is a top schematic view of an embodiment of the presentinvention.

FIG. 21 is a bottom view of a capacitor formed by the invention.

FIG. 22 is a cross-sectional schematic view taken along line 22-22 ofFIG. 21.

FIG. 23 is a cross-sectional view of an embodiment of the presentinvention illustrating a lap line.

FIG. 24 is a cross-sectional view of the embodiment of FIG. 23 afterfurther processing.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described with reference to the various figuresforming an integral non-limiting part of the disclosure. In the variousfigures similar elements will be numbered accordingly.

Described is a process for forming a capacitor utilizing a channel in acarrier strip followed by lap and dice cutting to form discretecapacitors.

A capacitor is generally understood to comprise two parallel conductorswith a dielectric therebetween. For the purposes of the presentinvention neither the composition of the conductors nor that of thedielectric is particularly limited. By convention the anode is thepositive terminal and the cathode is the negative terminal, though somecapacitor designs can be used without consideration of orientationwithin the circuit. For the purposes of the present invention aconductive foil will be defined as the anode and the cathode is formedduring exercise of the invention. It is to be understood that thisnomenclature is for convenience of discussion without necessarilylimiting the manner in which the capacitor is used within a circuitunless stated otherwise.

A channel carrier is illustrated schematically in FIG. 1. In FIG. 1, thecarrier, generally represented at 10, is a solid, conductive, preferablymetal, carrier strip having a channel, 12, with at least one side wallwhich is preferably centrally located. The channel width is preferablyslightly more than the conductive foil, 20, resident therein. Theconductive foil is typically slightly more than twice the width requiredfor a finished capacitor. The channel is preferably milled with a flatfloor most preferably with height variations along the surface of thechannel of no more than 0.0025 mm. At least one channel side wall whichis substantially perpendicular to the channel floor is preferred. It ismost preferred that the channel have two side walls.

The channel sidewalls, 16, may be cross-cut, 13, as illustratedschematically in FIGS. 2 through 4, which are at an angle relative tothe channel with perpendicular being most preferred. The cross-cuttingincreases structural integrity of the final device by lending physicalsupport to the later applied encapsulant which will be further describedherein. The shape of the cross-cut is not particularly limiting andincludes rectangular, diverging away from the bottom, or “T”-shaped.

The top surface of the carrier, 10, may have a conductive, preferablymetal, layer, 18, coated thereon wherein the conductive layer ispreferably selected from nickel, tin, copper, palladium, gold, lead, acombination thereof, or a combination of at least one of these metalswith an additional metal which is resistive to oxidation. The conductivelayer of the top surface may be applied by any method known in the art,including plating, sputtering, or other methods wherein a thin layer ofdeposition is prepared. The conductive layer forms anoxidation-resistant electrical connection between the carrier strip andthe cathode of the eventual capacitor and prevents increases inresistance when the assembled capacitor is exposed to moisture.

A strip of conductive foil, 20, is centered inside the channel of thecarrier and preferably adhered to the channel floor using an adhesive,25, preferably a low-viscosity adhesive. A particularly preferredadhesive is a polyimide. For the purposes of the present invention, theterms “foil” and “sheet” are used interchangeably. The conductive foilcomprises a conductive layer, 22, which ultimately forms the anode, andis preferably a valve metal, preferably aluminum, tantalum, niobium ortitanium, a conductive metal oxide such as NbO, or a combinationthereof, or conductive polymeric material. A dielectric layer, 24, isformed on at least the surface which is away from the adhesive, 25. Thedielectric is preferably an oxide of the anode material. It ispreferable to have only one dielectric layer since the dielectric layerfacing the adhesive will be sacrificed during manufacture. Metal foilwith a single oxide layer is not commercially available under favorableterms, thereby necessitating the use of a foil with both sides oxidized.It is preferred that the surface of the anode is roughened to increasethe surface area prior to anodizing to form the oxide dielectric.

The strip of conductive foil is preferably slightly wider than twice thewidth of the foil required in the finished product. It is important thatno physical or electrical contact be made between the strip ofconductive foil and the channel side walls. The strip of conductive foilis preferably approximately centered. The depth of the channel should beno less than the thickness of the conductive foil such that the finalcathode layer may establish electrical connection with the carrierwithout contacting the edges of the foil.

As illustrated schematically in FIGS. 5 and 6, an insulative material,26, is applied to the side walls of the carrier, filling the gap betweenthe carrier and the conductive foil. It would be apparent that theinsulative material is electrically insulating otherwise high leakagecurrent would be realized in the final product. The insulative materialis preferably a polymer solution having a viscosity which is high enoughto prevent bleeding onto the foil strip as this would reduce theavailable functional capacitance area. The viscosity of the polymersolution is preferably low enough that the material can penetrate intothe roughened surface of the valve metal.

A singulation dam, 28, is formed to pattern discrete capacitor elements.The singulation dam is preferable formed from a high viscosity,electrically insulating polymeric material. The viscosity is similar tothat of the insulative material. The singulation dam is applied by anymethod known in the art for printing a polymeric layer including screenprinting or direct application methods such as by syringe, by brush orby a transfer wheel. The singulation dam and insulative material insurethat the later applied cathode layer does not contact the cut edges ofthe foil which would cause electrical shorts during subsequentsingulation.

In an alternative embodiment, a conductive foil with a dielectricthereon and a conductive layer on the dielectric may be prepared as alayered structure and the layered structure inserted into the channel.The singulation dam may be excluded or applied to the layered structureprior to inserting the layered structure into the channel. After thelayered structure is inserted into the channel, the insulation materialis then added.

As illustrated schematically in FIG. 7, a cathode layer, 30, is formedon the exposed dielectric layer, 24. The cathode layer is a solidelectrolyte. The solid electrolyte layer may consist of one or morelayers of one or more conductive polymers. Preferred conductive polymersinclude polypyrrole, polyaniline and polythiophene. The conductivepolymer may be applied from a solution or suspension or the conductivepolymer may be formed in-situ by coating a monomer and oxidizersequentially. In-situ formation is less preferred due to thecomplexities of incorporating the process into conventional in-lineautomated processes since the number of process steps is necessarilyincreased with in-situ formation. Furthermore, in-situ polymer formationtypically provides a thicker, less dense, polymer layer which is lessdesirable in most applications. The polymer layer is applied by anytechnique available in the art, without limit, with exemplary methodsincluding ink jet printing, screen printing, gravure coating or maskedspraying. The cathode layer may comprise a manganese dioxide layereither in addition to a polymer layer or instead of the polymer layer.The manganese dioxide layer is preferably formed by applying a solutionof a manganese compound, such as manganese nitrate or a permanganate,followed by converting the manganese compound to manganese dioxide byheat. It is preferable that the manganese dioxide layer be depositedprior to deposition of the polymer; however, they can be added as amixture.

As illustrated schematically in FIG. 8, a carbon layer, 32, ispreferably applied over the cathode layer. The carbon layer improvesadhesion between the solid electrolyte cathode layer, 30, and subsequentconductive layer, 34, and is therefore preferred. The carbon layer isformed on the patterned surface of the solid electrolyte layer byapplying a paste, or thick ink, containing carbon particles preferablyin the form of graphite or carbon black. The carbon layer can be appliedby ink jet printing, screen printing, gravure printing or by sprayingwithout limit thereto. It is also desirable to apply a solder layer overthe carbon layer; however, the subsequent conductive layer may renderthe solder layer unnecessary. The solder layer, if applied, can be inthe form of a solder paste or a conductive paste. The solder layer isadded as a coating on top of the conductive layer. The solder layerfacilitates connection of a surface mountable device.

A conductive layer, 34, is added to form electrical conductivity betweenthe cathode layers and the conductive layer, 18. The conductive layermay be a silver, copper, gold, or other highly conductive metal orcombinations thereof. Particularly preferred is a silver, copper orsilver/copper ink or paste. The layer may be deposited by ink jetprinting, screen printing, gravure printing, spraying, sputtering,atomic layer deposition or other means for applying a thin layerdeposition.

After formation of the capacitive layers, a protective layer orencapsulant, 36, is formed on at least a portion of the carrier strip asillustrated in schematic side view in FIG. 9 and schematic top view inFIG. 10. The encapsulant is preferably an insulating polymer which, whencured, provides some rigidity and resistance to mechanical wear duringend-of-line processes and customer use as typically employed incapacitors. Preferred materials, not limited thereto, include resins,polyimides, epoxies, glass-filled epoxies, silicones and the like.

After encapsulation, a multiplicity of capacitors is contained withinthe carrier. For use, it is preferable to separate the discretecapacitors from the carrier. The anode which is the conductive foil, 22,is exposed by removing those portions below the plane defined by the lapline, 38, of FIG. 9. It would be apparent that the removal of thecarrier and dielectric, if present, exposes the conductive foil whichacts as the anode. In practice, a small portion of the anode is removedto insure a clean surface of anode material; however, the amount ofanode removed is preferably minimized due to cost and timeconsiderations. The capacitors can then be separated, or singulated, bycutting along dice lines, 40. Six discrete capacitors are illustrated inFIG. 10 without limit thereto. In one embodiment, adjacent units canremain together thereby forming a capacitor with two distinct cathodesand a common anode. The number of capacitors formed in this manner canbe very large. It would be apparent that the number of capacitors formedper carrier is a function of the size limitations of the manufacturingequipment and efficiencies and is not limited by the inventive process.

Lap cutting, as used herein, refers to a cutting operation which makesthe anode accessible and is typically substantially parallel to theanode and refers to any mechanical means of forming a cut which issubstantially parallel to the anode face. Exemplary methods includeplaning, lapping, sand blasting, single point diamond turning, grinding,routing and the like. In the present invention, it is most desirable tolap cut the entire carrier. However, discrete regions can be lap cutsuch that the discard areas between capacitors are not cut.

Dice cutting, as used herein, refers to a cutting operation whichseparates discrete capacitors from the carrier or from each other and isnot parallel to the anode and is preferably substantially perpendicularto the anode. Exemplary methods include saw dicing, blade dicing, waterjet cutting, laser cutting and the like.

It is preferable to expose the anode prior to dice cutting. However,dice cutting can be done first and then the individual capacitors lapcut to expose the anode.

After lap and dice cutting discrete capacitors are provided with theremaining carrier forming the cathode connection and the exposed metalof the metal foil forming the anode connection based on conventionalterminology.

An embodiment of a finished capacitor is illustrated in cross-sectionalschematic view in FIG. 11 and in schematic bottom view in FIG. 12. Thecapacitor, generally represented at 50, comprises an anode, 52, which isthe exposed conductive foil. The dielectric, 54, separates the cathode,56, from the anode. The cathode may include multiple layers if necessaryor it may be a single conductive layer. A conductive layer, 58,electrically connects the cathode to a cathode lead, 60, which is thatportion of the carrier remaining after lap and dice cutting. Primaryinsulative material, 62, separates the anode and cathode and secondaryinsulative material, 64, insulates the edge of the anode. Anencapsulant, 66, electrically isolates the upper side if this side isnot intended to be subsequently connected to a circuit trace.

Another embodiment of a finished capacitor is illustrated in schematiccross-sectional view in FIG. 13 and schematic bottom view in FIG. 14. Inthe embodiment of FIGS. 13 and 14 the carrier was originally crosscut asdescribed above. In the finished capacitor the cathode lead out, 68,does not extend the entire width of the capacitor but is insteadsandwiched between insulative islands, 70.

Another embodiment is illustrated in schematic cross-sectional view inFIG. 15. In FIG. 15, the anode, 22, is oxidized on a single side whereinthe oxide forms the dielectric, 24. A solid cathode layer is illustratedat 30 with discrete areas separated by singulation dams, 28. Aconductive layer, 72, is in electrical contact with the cathode. Theconductive layer allows adequate adhesion between the eventual capacitorand the circuit trace and is desirable due to the difficulty in formingan electrical connection directly with a solid cathode layer. There ispreferably no encapsulating layer, or a limited area encapsulation, inthis embodiment. The lap line, 74, is coplanar with the lower extent ofthe anode. If necessary, the lap line may be slightly interior to theanode thereby sacrificing a small portion of the anode to insure a cleansurface. The dice lines, 76, separate the discrete capacitors within theinsulative material, 26, and singulation dam, 28. After dicing andlapping, in either order, discrete capacitors are obtained with opposingpolarity on opposite faces.

Another embodiment is illustrated in cross-sectional side view in FIG.15 a as a modification of the embodiment of FIG. 15. In FIG. 15 a, thesingulation dam, 28, is lower than the top layer cathode layer such thatthe cathode, 30, is in electrical contact either by the cathode layer,30, being at least partially continuous, or by the conductive layer, 72,being in electrical contact with both cathode layers. Alternatively, thesingulation dam can be eliminated. A kerf, 151, separates the anode intotwo distinct elements thereby forming a capacitor with a common cathodeand individual anodes. The capacitor can be singulated by cutting at thedice line, 76, to form a non-polar device or a portion of the carriercan remain to form a capacitor with coplanar terminations. If a facedown capacitor is desired at least the conductive layer, 72, preferablyoverlaps the carrier as described elsewhere herein.

The capacitor may be polar or non-polar. Referring to FIG. 15, thefinished capacitor will have two conductors separated by a dielectricwherein one conductor is defined as the anode and the other as thecathode. Capacitors having a common anode internal to the device withmultiple discrete cathode terminals or a common cathode internal to thedevice with discrete anode terminals have no preferred orientation inelectrical circuitry and therefore are referred to as non-polar.Capacitors having both anode and cathode terminals have a distinctorientation in electrical circuitry and are referred to as polar.

A particular feature of the present invention is the ability to form acapacitor with thin layers which would otherwise be difficult tomanufacture. Capacitive elements with a thickness of less than 250 μm,as measured from the cathode face to the opposing anode face, can easilybe formed with the present invention. The ability to manufacture acapacitor with thin active layers increases the capacitive volume whichis an ongoing desire in capacitor manufacture. The present inventionallows for the manufacture of a capacitive couple, being the anode,dielectric and cathode, of about 10 μm to about 250 μm thick. Morepreferably, the present invention allows for the manufacture of acapacitive couple which is less than 100 μm and more preferably lessthan 50 μm thick.

A particularly preferred carrier is illustrated in schematic topperspective view in FIG. 16. In FIG. 16, the carrier, generallyrepresented at 160, comprises a multiplicity of channels, 159. Aconductive layer, 168, may be on the top surface, 169, of the channelcarrier.

FIG. 17 illustrates the multi-channel carrier in schematic top view andFIG. 18 illustrates a schematic cross-sectional view taken along line18-18 of FIG. 17. FIGS. 17 and 18 are prior to singulation. In FIGS. 17and 18, each channel has an anode, 161, with a dielectric, 162, thereon.An insulative material, 163, separates the anode from the side walls ofthe channel. Singulation dams, 164, form discrete regions within whichthe cathode, 165, is formed. As would be realized, the cathodepreferably has additional layers such as a carbon layer, a metal layer,and a solder layer to facilitate attachment of the capacitor to anelectrical circuit. The capacitors would be singulated as describedherein by lap cutting to expose the anode and dice cutting in theinsulative material.

Another embodiment is illustrated in schematic cross-sectional view inFIG. 19. In FIG. 19, the carrier, 160, has multiple channels. Eachchannel has therein anodes, 161, dielectrics, 162, insulative materials,163, singulation dams, 164, and cathodes, 165, as described above. Aconductive layer, 166, electrically connects the cathode, 165, to thecarrier, 160, preferably through a metal layer, 168. An insulator layer,171, can be applied to the top surface if desired.

To form discrete capacitors the excess carrier is removed by cuttingalong the lap line, 170, approximately parallel to the floor of thechannel to expose the anode. The capacitors can be singulated by dicecutting along dice lines 172 or along lines 173 depending on the type ofcapacitor desired. It would be apparent to one of skill in the art thatdice cutting along dice line 172 would form a capacitor with the anodeand cathode on opposing faces. In this instance it would be desirable toforego the conductive layer and insulator layer otherwise the cathodecan be otherwise accessed. If cut along dice lines 173 a capacitor withanode and cathode terminations on a common face is prepared.

A particularly preferred embodiment is illustrated in schematic top viewin FIG. 21. In FIG. 20, the carrier, 210, has a multiplicity of pockets,211. Each pocket has positioned therein a centrally located anode withan oxide coating thereon, 212. Between the anode and the walls of thepocket is an insulative material, 213. A cathode is deposited on thedielectric as described herein as is a preferable conductive layerelectrically connecting the cathode to the carrier (not shown). Afterformation of the cathode, the carrier is preferably lap cut to exposethe anode and dice cut along dice lines. The resulting capacitor isillustrated in bottom schematic view in FIG. 21 and schematiccross-sectional view in FIG. 22. In FIGS. 21 and 22 the anode hasinsulative material circumjacent thereto and the insulative material hasthe cathode circumjacent thereto.

In FIGS. 21 and 22 the capacitor, generally represented at 220, isparticularly advantageous due to the absence of any rotationallimitations in mounting. The capacitor comprises a centrally locatedanode, 221, with a dielectric, 222, thereon. An insulative material,223, separates the anode and carrier, 224. A cathode, 225, is inelectrical contact with the carrier through a conductive layer, 226, onthe cathode and conductive coating, 227. The carrier forms a cathodeconnection around the exterior of the capacitor with an anode connectioncentrally located thereon with both on a common face.

An alternate embodiment is illustrated in FIG. 23. In FIG. 23 aconductive foil, 230, comprising dielectric, 232, on each face, iscoated on one face and an edge with an insulative material, 233. Acathode layer, 234, is then formed over the insulative material anddielectric. An optional, but preferred, conductive layer, 235, is coatedon the cathode layer to form a capacitive element. The capacitiveelement is then secured to a conductive carrier bar, 236, with aconductive adhesive, 237, and the entire assembly is optionally encasedin an encasement material, 238, which is not electrically conductive.The assembly is then lap cut along line 239 resulting in at least onecapacitor having anode and cathode terminals on the same face asillustrated in cross-sectional view in FIG. 24.

The anode is a conductor preferably selected from a metal or aconductive metal oxide. More preferably the anode comprises a mixture,alloy or conductive oxide of a valve metal preferably selected from Al,W, Ta, Nb, Ti, Zr and Hf. Most preferably the anode comprises at leastone material selected from the group consisting of Al, Nb and NbO.Conductive polymeric materials may be employed as an anode material.Particularly preferred conductive polymers include polypyrrole,polyaniline and polythiophene.

The cathode is a conductor preferably comprising at least one ofmanganese dioxide and a conductive polymeric material. Particularlypreferred conductive polymers include polypyrrole, polyaniline andpolythiophene. Metals can be employed as a cathode material with valvemetals being less preferred. The cathode may include multiple layerswherein adhesion layers are employed to improved adhesion between theconductor and the termination. Particularly preferred adhesion layersinclude carbon, silver, copper, or another conductive material in abinder.

The dielectric is a non-conductive layer which is not particularlylimited herein. The dielectric may be a metal oxide or a ceramicmaterial. A particularly preferred dielectric is the oxide of a metalanode due to the simplicity of formation and ease of use.

The invention has been described with particular reference to thepreferred embodiments without limit thereto. One of skill in the artwould realize additional embodiments which are not specifically recitedbut within the scope of the claims appended hereto.

1-72. (canceled)
 73. A capacitor comprising: a metal foil anodecomprising a bottom and top; a dielectric on said top of said metal foilanode; a cathode on said dielectric opposite to said metal foil anode; acathode lead in electrical contact with said cathode on a first facewhere a second face of said cathode lead is coplanar with said bottom ofsaid metal foil anode; and an insulator on two opposing sides of saidcathode lead different than said first face and said second face. 74.The capacitor of claim 73 further comprising an insulative coating on atleast one face selected from a face opposite to a face comprisingterminals and a face adjacent to a face comprising terminals.
 75. Thecapacitor of claim 73 wherein said anode is wider than said cathodelead.
 76. The capacitor of claim 73 further comprising an insulatorbetween said anode and said cathode lead.
 77. A capacitor comprising: ametal foil anode comprising a bottom and top; a dielectric on said topof said metal foil anode; a cathode layer on top of said dielectric;said metal foil anode has a cathode lead circumjacent thereto; a cathodelead in electrical contact with said cathode; and an insulator betweensaid cathode lead and said metal foil anode.
 78. The capacitor of claim77 further comprising an insulative coating on at least one faceselected from a face opposite to a face comprising terminals and a faceadjacent to a face comprising terminals.
 79. The capacitor of claim 78wherein said metal foil comprises metal or a conductive metal oxide. 80.The capacitor of claim 79 wherein said metal foil anode comprises atleast one conductor selected from Al, W, Ta, Nb, NbO, Ti, Zr and Hf. 81.The capacitor of claim 80 wherein said conductor is aluminum.
 82. Thecapacitor of claim 80 wherein said dielectric is an oxide of said metalfoil anode.
 83. The capacitor of claim 78 wherein said cathode layercomprises manganese dioxide or a conductive polymeric material.
 84. Thecapacitor of claim 83 wherein said conductive polymeric material is anintrinsically conducting polymer.
 85. The capacitor of claim 78 whereinsaid cathode layer comprises manganese dioxide or a conductive polymericmaterial.
 86. The capacitor of claim 85 wherein said conductivepolymeric material is an intrinsically conducting polymer. 87-92.(canceled)